system-helper: Do not ask for password when removing apps/runtimes
system-helper: Do not ask for password when removing apps/runtimes

As it's already done for installing an app or runtime, we shouldn't ask
privileged users to authenticate in order to remove them.

matthiasclasen/flatpak,handsome-feng/flatpak,flatpak/flatpak,flatpak/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,handsome-feng/flatpak,flatpak/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,handsome-feng/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,handsome-feng/flatpak,GeorgesStavracas/flatpak,matthiasclasen/flatpak,GeorgesStavracas/flatpak,flatpak/flatpak,GeorgesStavracas/flatpak